This invention relates to the regulation of the power supply voltage for a motor vehicle having at least one high-power operating component, such as a starter for an internal combustion engine, and one or more lower-power components such as a lighting circuit.
In the past, during normal operation of a motor vehicle, the internal combustion engine was turned off only in exceptional cases, and only when the vehicle was stationary. More recently, experiments have been carried out in which the internal combustion engine is turned off while the vehicle is coasting, or during brief stops, for the purpose of saving energy. In these conditions, the operation of the electrical components in the vehicle that are normally supplied by the vehicle generator when the engine is running must be continued, especially when the vehicle is still coasting, for example, in the driven mode. The battery provided with the vehicle must be designed to satisfy this requirement but, when the engine is restarted, the starter places a heavy load on the battery. As a result, the voltage in the power supply circuit of the vehicle drops abruptly. Certain electrical components such as a radio may suffer a loss of function because of this sudden voltage drop. In addition, a distinctly noticeable flicker will occur in the vehicle lights, especially the headlights and tail-lights.